For an economical production of milk, the complete emptying of the udder is of greatest importance. We thereby do not only deal with the milk and fat amounts which are obtained directly during each milking. The degree of emptying of the udder influences also the course of the lactation curve, thus the stamina of the cow and the milk output in the next following lactation sections. Furthermore, poorly emptied udders are increasingly subject to udder diseases.
A condition for an as high as possible degree of udder emptying is, aside from a full stimulation of the milk ejection process of the cow and a gentle and quick milk removal procedure, an as much as possible complete recovery of the available residual milk at the end of the milking process.
The residual milk phenomenon is explained by the anatomic structure of the udder. Between the large milk storage chamber of the udder (gland cistern) and the smaller storage chamber of the individual teat (teat cistern) there is provided at the level of the teat base an inner annular fold (Fuerstenberg'sche Venenring). At the lower end of the teat cistern is the streak canal which is closed in the normal condition, which canal forms the port of the teat to the outside. During milking, the annular fold between the gland and teat cisterns is open wide during the highest milk flow rate. The length and the radial expandibility of the streak canal determines the milk resistance (flow resistance) on the udder. This means that the milking vacuum is not continued into the teat cistern. The inner pressure in the teat of a cow ready to be milked lies between approximately 30 to 60 mbar. above the atmospheric pressure, so that the teat under the action of the milking vacuum rests fully on the teat rubber which supports said teat.
With an increase in udder emptiness, the pressure on the inside of the udder slowly decreases and the annular fold slowly narrows down. Starting from a certain point in time, less milk can flow through the annular fold into the teat cistern, than is sucked out through the streak canal. As a result, not only does the milk flow diminish, but at the same time the milking vacuum moves now into the teat cistern. This causes the earlier full teat to relax and the teat cistern is now compressed during each relief cycle, which causes the inner mucous membranes of the cistern lining to be rubbed against one another. This causes pain to the cow, which leads to a further blockage of the cow's milk yield. If the mechanical milking operation is continued beyond this point in time, then this may lead to injury to the structure of the udder. At the time, when the milking vacuum penetrates into the teat cistern and the milk flow stops, milk will, however, still flow into the gland cistern, which is no longer automatically mechanically milked. Therefore, following the mechanical milking process, a time-consuming procedure is required to obtain a finish milking. This finish milking stage takes up a considerable portion of the routine time of a milking person, which he or she must spend per cow.
In order to achieve an as much as possible gentle mechanical milking action and in order to permit an automatic finish milking, German Pat. No. 25 39 868 already discloses a method, in which first at the start of the milking operation and during approximately two minutes independent of the milk flow rate, a high milking underpressure is applied and in which after this time is over, the milking underpressure is controlled such that, when falling below a milk flow rate of approximately 0.5 l/min., the milking underpressure is switched over to a lower finish milking underpressure. A similar method has already become known from German Pat. No. 19 56 196, in which simultaneously with the switching over from a milking underpressure to a lower finish milking underpressure, when falling below a predetermined milk flow value, the same reduced finish milking underpressure is transmitted also into the space between the suction insert and the milking cup housing as a pulsation underpressure. Also this reference already describes a method in which, dependent on the falling below of a predetermined milk flow value, the relationship between the durations of the pressure and suction periods of the pulsation underpressure is changed such that during a large milk flow interval, the suction period is long and during a small or no milk flow period, the suction period is short. Also this reference discloses a method in which during the finish milking stage, the pulsation frequency is considerably reduced with respect to the milking stage. Also German OS No. 25 24 398 already discloses a method, in which for the gentle treatment of the teat during the finish milking stage, the pressure inside of the suction insert is held at the normal underpressure, however, the underpressure applied during the pulsation is reduced so that the walls of the suction insert rest on the teat so that only the tip of the teat and not the entire teat is exposed to the underpressure inside of the suction insert.
From German OS No. 24 14 107 furthermore a method is already known, in which an injury of the teat during the finish milking stage is avoided and an automatic finish milking is achieved by lowering the pulse frequency of the pulsator when falling below a pregiven milk flow rate, without causing the vacuum inside of the suction insert, namely in the milk discharge line, to be changed with respect to the milking underpressure.
From Australian Pat. No. 109 446 an apparatus has also already become known, in which the milking underpressure can be controlled proportionally with respect to the respectively existing milk flow. This means, if at the start of the milking operation no or only a small milk flow exists, a small milking underpressure is applied, which is enlarged to the degree that the milk flow increases. At the end of the milking operation, the milking underpressure is then reduced again at the same degree that the milk flow is reduced. Such a milking method is, however, not suitable for cows which are difficult to milk, since here especially right from the start a high milking underpressure is needed in order to at all achieve an acceptable milk flow. Furthermore the milking method can lead, especially in the case of cows which are difficult to milk, to physiologically unfavorable long milking times, so that the cow which must be milked loses already due to the long milking time the willingness to further give milk even though a substantial amount of milk has not yet been milked off.
Also it has already been tried to apply a constant, however, substantially smaller milking underpressure than is usually common. This, however, leads automatically to physiologically unfavorable long milking times, which reduces the amount of milk given as a whole.
German OS No. 26 46 596 also already discloses an apparatus for the automatic finish milking after falling below a predetermined milk flow rate, in which with the help of a linkage and a cable line, which is swung under the cow and which engages the milking tool, at the start of the finish milking stage a vertical or inclined pull is applied downwardly onto the milking tool.
A similar pneumatically operated arrangement has already become known from German OS No. 1 278 166, in which the entire milking tool is held on a horizontally movable and a vertically movable arm. This arrangement is controlled pneumatically at a reduction of the milk flow rate below a value of 0.4 kg/min. such that through the milking cup a downwardly directed force is applied onto the teat, which is supposed to achieve an intensification of the milk discharge. This downwardly directed pull onto the milking cup is maintained during the entire so-called finish milking stage, until the milk flow rate falls below a value of 0.2 kg/min, after which the entire milking tool is pulled off automatically.
While it is possible with the last mentioned apparatus, with which in the finish milking stage a downwardly directed pull onto the milking tool is applied, a substantially independent finish milking can be achieved, if desired, such an automatic finish milking cannot be carried out successfully by changing the milking parameters. Such devices, however, with which a vertical pull onto the milking tool can be applied during the finish milking stage, have the important disadvantage that they strongly limit the freedom of movement of the milking tool on the cow during the milking process and thus simultaneously interfere with the willingness of the cow to give milk. Furthermore such devices can only be utilized in milking stalls. On the other hand, such a device is technically very expensive and at least in practice very susceptible to trouble. Furthermore, a considerable risk of injury to the cows exists through the use of such devices.
According to the present invention. I have discovered that the possibility of the automatic finish milking depends decisively from the position the teat rubber of the milking cup is at during the finish milking stage.
As was already discussed above, a cow which is ready to be milked has a teat innerpressure of approximately 30 to 60 mbar. above the atmospheric pressure so that the teat under the action of the milking underpressure rests fully on the teat rubber which supports it. Thus a strong friction exists between the teat and the teat rubber, through which, when equilibrium exists between the milking tool weight and the milking underpressure, a climbing up of the milking cup on the teat due to the suction action of the milking underpressure is prevented. However, starting from a certain point in time, as soon as less milk flows into the teat cistern, due to a slow narrowing down of the annular fold, than is sucked out through the streak canal due to the milking underpressure, the milking underpressure moves on into the teat cistern. As a result, the underpressure in the teat cistern rises until the pressure difference between the underpressure in the teat cistern and the milking underpressure is reduced so low, that based on this small pressure difference the streak canal is no longer being opened. The pressure difference, at which the streak canal opens up, varies between 0.15 and 0.5 bar. In the medium value the pressure difference lies between 0.20 and 0.25 bar, whereby cows, which need a pressure difference of 0.25 bar before a milk discharge occurs, are already identified as cows which are difficult to milk. As soon as the underpressure moves on into the teat cistern, the earlier full teat relaxes within approximately 3 to 10 pulsation cycles. This reduces the friction between the teat rubber and the teat and the milking cup moves upwardly on the teat in direction of the teat base due to the suction action of the milking underpressure, until a new force equilibrium is achieved. The danger of the milking cup climbing up on the teat is thus greater in the case of cows which are difficult to milk. This climbing of the milking cup up on the teat causes the upper enlarged head of the teat rubber to apply an additional pressure on the annular fold at the lower end of the gland cistern and totally contracts the annular fold from outside. This causes the loosening of the muscle tone of the smooth udder muscles of the cow to stop prematurely, since the cow has in this gland area particularly sensitive pressure and contact receptors, which are extremely sensitive to the pressure of the enlarged head of the teat rubber. This results in the cow feeling unwell and closing herself the muscle, which blocks the milk flow. The action of the enlarged head which blocks the milk flow is further enhanced by the milking underpressure moving into the head of the milking cup during a climbing of the milking cup up on the teat, which causes the extremely sensitive teat tissue to be exposed at the base of the teat below the contracting annular enlarged head of the teat rubber to the full milking underpressure, without supporting the teat tissue in this area by the teat rubber. This procedure causes the cow to have an additional pain, which leads to the cow further blocking the milk discharge. Thus the milk which still flows from the milk gland into the gland cistern can no longer be removed. The amount of this loose residual milk amounts on the average to almost 500 g. per milking with a variation range of 0 to 2000 g. This high amount of residual milk today does not permit a finish milking for reasons of the entire production and the health of the udder. In order to be able to withdraw this finish milk, the closing of the annular fold must be reversed. This can be achieved by applying such a high force onto the milking cup or onto the milking tool, that the milking cups are lowered on the teat. However, this operation must take place immediately after the milk flow stops in the teat, in order to avoid an udder damaging blind milking.
As will be discussed more in detail further below, it has been discovered that in the case of milking methods which have been known up to now which effect changes of the milking parameters in the finish milking stage, the milking cups have mostly already climbed up on the teat, before the actual finish milking stage starts. As was discovered, however, a finish milking of the finish milk can no longer be achieved by a change of the milking parameters even if the milking cup has already climbed up on the teat. A manual or mechanical handling of the milking cup is then needed in order to again guide the milking cups downwardly on the teat and to hold them in a lowered position in order to be able to withdraw also the finish milk. A manual lowering of the milking cup by the milker requires, however, much work. A mechanical apparatus for lowering the milking tool is extremely complicated and brings about a considerable risk of injury to the cows.
Therefore, the basic purpose of the present invention is to provide a method for the automatic finish milking during a mechanical milk removing process, in which a premature blocking of the passage between the gland cistern and the teat cistern is prevented prior to the complete emptying of the udder.
This purpose is inventively attained starting out from a method of the above-mentioned type of continuously measuring or detecting the change of the milk flow per unit of time and by initiating a reduction of the milking intensity directly after a reduction of the milk flow rate of more than 1 kg/min.sup.2, which reduction is determined during a period of time of 5 to 10 seconds.
This abrupt reduction of the milk flow rate at the end of the main milking stage is in the case of every cow an unerring sign indicating the beginning of the end of the main milking stage. At this point in time, the teat is still full, the passage between gland cistern and teat cistern is not yet blocked, and the milking cup has not yet climbed up on the teat. By directly reducing the milking intensity at this time, a blocking of the passage between gland cistern and teat cistern and the climbing of the milking cup up on the teat, which is effected secondarily through this, can be prevented. As a result of this measure, an unhindered further milk flow up to the total finish milking can be maintained.
A second solution to the aforementioned problem consists in providing a method for the automatic finish milking during a mechanical milk removal process, in which the teat which is introduced into an elastic teat rubber of the milking cup is exposed to a predetermined underpressure and a pulsating underpressure is applied to a space between a milking cup housing and the teat rubber which encloses the teat, the measurement of a milking parameter is carried out continuously and the milking intensity is reduced dependent on the result of the measurement, which is characterized by the continuous measurement being the detecting of the pressure in the inner chamber of the head of the teat rubber below the ring lip which rests against the teat and by effecting a reduction of the milking intensity at the start of a lowering of said pressure.
As a result of this, a further possibility exists for the automatic control of the milking operation. However, this possibility of control is not as exact as the first mentioned control possibility, since a lowering of the pressure in the inner chamber of the head of the teat rubber occurs most of the time not before the teat has already substantially relaxed so that a climbing of the teat rubber up on the teat is eminent.
Through both inventive solutions, it is achieved that a blocking of the passage between the gland cistern and the teat cistern and thus a climbing of the milking cup up on the teat is prevented. As a result, a substantially better automatic mechanical udder emptying is achieved, particularly with substantially lesser finish milking amounts. Through this the finish milking manipulations of the milking person can be limited alone to the so-called control handling. A finish milking by hand is in every case no longer necessary. Particularly preferable is the use of the inventive method in milking systems with automatic milking tool removal, which occurs with a timely delay, when the milk flow has stopped. By using such automatic milking tool removing devices so far, the loose residual milk remained in the udder and this was caused by the system with the consequence of increased mastitis problems and poorer milk outputs of the cows.